Antistatic paper



United States. Patent F 3,082,123 ANTISTATIC PAPER Franklin Y. Chu, Rochester, N.Y., assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed Oct. 24, 1960, Ser. No. 64,251

. 8 Claims. (Cl. 117154) This invention relates to paper to which antistatic properties have been imparted by treating with the disodium salt of 2,7-naphthalenedisulfonic acid or of l-naphthol- 3,6-disulfonic acid.

The use of partially acetylated paper particularly for photographic purposes has become of interest because of its dimensional stability and other improved properties as compared to paper made from cellulose having no groups chemically combined therewith. A disadvantage of partially acetylated paper is its proneness to generate static electricity when used in the manufacture of photographic products. The surface resistance of partially acetyl-ated paper is higher than that of non-acetylated paper and most of the hydrophilic or conductive inorganic or organic salts cannot be used as an antistatic agent therewith. More specifically, those antistatic agents do not lower the resistance values :of the paper to a desirable level.

One object of my invention is to provide paper having improved antistatic properties. Another object of my invention is to provide a partially esterified paper useful in manufacturing operations, as the preparation of photographic products, free of difficulty arising from the generation of static electricity. A further object of my inven tion is to employ the disodium salt of 2,7-naphthalenedisulfonic acid or l-naphthol-3,6-disulfonic acid as an antistatic agent for paper, particularly that which has been acylated. Other objects of my invention will appear herein.

I have found that the surface resistance of paper can be considerably lowered if that paper is supplied, particularly on the surface thereof, with :a content of a disodium salt of 2,7-naphthalenedisulfonic or l-naphthol- 3,6-disulfonic acid. These salts are conveniently added by applying to the paper either in the form of its aqueous solution or a solution thereof containing a binder to aid in binding the salt on the surface of the paper.

Partially acylated cellulose paper has been referred to as being useful particularly for photographic purposes as described in Richter and Herdle application Serial No. 755,418, filed August 18, 1958, Griggs and Zafiran application Serial No. 786,041, filed January 12, 1959,

now abandoned, and Griggs, Gray and Zalfran application Serial No. 22,710, filed August 18, 1960. Partially acylated papers exhibit good dimensional stability and are resistant to the effects of Water in liquid or vapor form. However, these papers are more susceptible to generation of static electricity than is ordinary paper. Therefore, although my invention relates to the treating of paper generally, it is of particular value for the treating of partially acylated paper such as is described in the various applications referred to above.

The antistatic material in accordance with my invention may be applied to the paper at the rate of at least 0.5 gram per square meter of paper. However; for most effective lowering of the surface resistance, it is desirable to apply approximately 1 gram of one of the Sodium salts referred to per square meter of paper surface. If the paper is readily susceptible to wetting by water, the antistatic agent can be conveniently applied thereto merely in the form of its solution in water. However, to assure adhesion of the coating to the paper, it is desirable that a binder be employed in the aqueous solution of the anti- 3,082,123 Patented Mar. 19, 1963 ice 2 static agent. Any inert binder can be employed. To illustrate, the following have been found to be useful as binders in the coating of paper with the antistatic materials to which the invention relates, carboxymethyl. hydroxyethyl cellulose and the like such as described in US. application Serial No. 700,555 of Illingsworth and Minsk, filed December 4, 1957, now Patent No. 3,003,878; zein, casein, gelatin or a copolymer such as described in US. Patents Nos. 2,739,137 and 2,772,166 of Fowler. The binder may be employed in amounts from V up tc as much as an amount equal to that of the antistatic agent employed. Although'the invention relates primarily tc partially acylated paper, the antistatic properties of ordinary paper are also improved by applying a coating thereon in accordance with the invention. Ordinarily, an application to one side of the paper is considered sufiicient but paper may be coated on both sides in accordance wit]: the invention if this is thought to be desirable.

The following example illustrates the preparation 01 paper having antistatic properties in accordance with my invention:

An aqueous solution was prepared containing 7% 01 the disodium salt of 2,7-naphthalenedisulfonic acid anc' /2 of carboxymethyl hydroxyethyl cellulose. This solution was surface coated on partially acetylated paper prepared by the methods described in applications Nos 786,041 and 22,710, the paper being of a base weight 01 13 pounds per thousand square feet. The paper sc treated was conditioned by holding at 20% relative humidity for a day and surface resistance measurement: were made thereon the results of which are shown in the following table which indicates, besides the surface re sistance measurements, the rates of application of the an tistatic material and the surface resistance measuremen of the partially acetylated paper having no antistatit coating.

Cover-age (gm/m Surface resistance (ohm-s] 1.00 1.6)(10 1.75 2X 10 2.42 1x10 Comparison 10 The coated paper when subjected to overexposure tc ultraviolet light exhibited no yellowing.

A coating operation similar to that described in tht preceding example was carried out but using the disodiurr salt of 1-naphthol-3,6-disulfonic acid as the antistatit agent. Surface resistance measurements showed a lowering of the surface resistance of the paper by coating witl this material similar to that obtained in the example.

We claim:

1. Cellulose sheeting containing on the surface of a least one side thereof, to impart antistatic propertie: thereto, a coating of an alkali metal di-salt of an acic' selected from the group consisting of 2,7-naphthalenedisulfonic acid and 1-naphthol-3,6-disulfonic acid at tilt rate of at least 0.5 gram per square meter of surface.

2. A paper sheet containing on the surface of at 16351 one side thereof an antistatic coating of an alkali meta di-salt of an acid selected from the group consisting o1 2,7-naphthalenedisulfonic acid and l-naphthol-3,6-disulfonic acid at the rate of at least 0.5 gram per square mete] of paper surface.

3. A cellulose paper having an apparent acetyl conten' of 15-25% containing on the surface of at least one sid thereof an antistatic coating of an alkali metal di-salt 01 an acid selected from the group consisting of 2,7-naphthalenedisulfonic acid and 1-naphthol-3,6-disulfonic acid a the rate of at least 0.5 gram per square meter of papei surface. a

4. A cellulose sheet containing thereon an antistatit 3 coating of the disodium salt of 2,7-naphthalenedisulfonic acid at the rate of at least 0.5 gram per square meter of surface.

5. A cellulose sheet containing thereon an antistatic coating of the disodium salt of 1-naphthol-3,6-dis-ulfonic acid at the rate of at least 0.5 gram per square meter of surface.

6. Partially acetylated paper having thereon an antistatic coating of the disodium salt of 2,7-naphthalenedisulfonic acid at the rate of at least 0.5 gram per square meter of surface.

7. Partially acetylated paper having thereon an antistatic coating of the disodium salt of 1-naphthol-3,6-disulfonic acid at the rate of at least 0.5 gram per square meter of surface.

8. Paper containing on the surface of at least one side References Cited in the file of this patent UNITED STATES PATENTS Gibson et a1. May 2, 1944 OTHER REFERENCES Uber die Vervendung von Siedenden Losungsmitteln zur Temperaturregelung bei der Reaktion von gasformigem Schwefeltrioxyd mit Naphthalein, vorgelegt von Werner Flachs, Juris-Verlag, Zurich, 1958, pp. 30-34. 

1. CELLULOSE SHEETING CONTAINING ON THE SURFACE OF AT LEAST ONE SIDE THEREOF, TO IMPART ANTISATIC PROPERTIES THERETO, A COATING OF AN ALKALI METAL DI-SALT OF AN ACID SELECTED FROM THE GROUP CONSISTING OF 2,7-NAPHTHALENEDISULFONIC ACID AND 1-NAPHTHOL-3,6-DISULFONIC ACID AT THE RATE OF AT LEAST 0.5 GRAM PER SQUARE METER OF SURFACE. 